Signaling system



March 25 1924. 1,488,167

SIGNALING SYSTEM i IF Filed Jan. 30 1920 IN VEN TOR.

6 [ma/M! mom/Ev Patented Mar. 25, 1924.

ROGER G. RAMSDELL. 0F BROOKLYN,

Zhidddt? AMERICAN TELE- OF KEV] YORK.

SIGNALING SYSTEM.

Application filed January 30, 1920.

Be it known that I, ROGER G. RAMSDELL, residing at Brooklyn, in thecounty of Kings and State of New York, have invented certainimprovements in Signaling Systems, of which the following is aspeciiication.

This invention relates to improvements in signaling systems and moreparticularly to that type of signaling system designed to transmit overa subscribe1"s telephone line a current of varying magnitude adapted toproduce in a telephone receiver that may have been left off its hookinadvertently or otherwise, tone of varying magnitude in order toattract the subscribers attention and to effect the restoration of thereceiver to its hook.

The copendingapplication of Kuhn and Ramsdell, Serial No. 355,175,filed'Jan. 30, 1920, shows means whereby, in a so called howler circuitadapted to apply a signaling potential to a subscribers telephonecircuit upon which the receiver has been left off its hook, the sourceof potential may be effectively disconnected from the subscriberscircuit upon the restoration of the receiver to its hook and will notagain be connected thereto until, the operator, who is responsible forthe application of the said signal to the line, has properly supervisedthe connection. An undesirable feature of the arrangement disclosed inthe aforementioned application, and in other arrangements heretoforeused, is that it is possible for an operator to apply the howlerelectromotive force to a line without first listening in on the line andchallenging in order to determine whether at that instant any party onthe line has the receiver to his ear.

It is well known to those familiar with telephone maintenance andoperation that the application to a subscribers line of a signalingcurrentof suflicicnt magnitude to produce in a receiver of asubscriberstelephone set. inadvertently left off its hook, a tone adapted toattract the subscribers attention and to effect the restoration of thereceiver to its hook, is undesirable from an operating standpoint, andthat the application of such current to a line should be made only aftercareful supervision indicates that no persons are at that. instantattempting to make a telephone call over the said line.

Serial No. 355,176.

Hitherto it has been customary to instruct all persons charged with theduty of applying the ho-wler signal to subscribers lines that theyshould first listen in upon the line and then challenge by someappropriate phrase, but mistakes are liable to occur, due to thefallibility of human nature, which may result in the application of thesignaling current to a line upon which some person has a receiver to hisear. It is the object of this invention to interlink the supervisoryprocess with the process of applying the signaling current in suchmanner that it is substantially impossible to apply the signalingcurrent to the subscribers line Without previously connecting theoperators telephone set with the said line, by which the propersupervision of the said line is reasonably assured.

Other and further objects of this invention will appear from thefollowing descrip* tion when read in connection with the attacheddrawing which shows one embodiment thereof.

In the drawing L represents a telephone linehaving associated therewithsubscribers stations A and A the former of wnirh is shown with itsreceiver off its hook. Associated with the said line are the line relayR and the cut-off relay The line L, may terminate at the switchboard ina jack J having a-line signal lamp 20 associated therewith. The howlercord circuit terminates in a plug P adapted for insertion into jack Jand has associated therewith a key K which when operated to the leftserves not only to connect the operators telephone set with the linewith which the plug P, may then be connected but also initiates theoperation for applying howlcr signals to the line; and when operatedtoward the right servesto complete the op erations by means of which thesaid signals may be applied'to the line.

Associated with the cord circuit are supervisory r lay R, and controlrelays R R and R which serve to control the conncction of the signalingelectromotive force with the line circuit. A source of vary ingelectromotive force G, is connected in series with the primarywinding'of the transformer T and ope ratively controlled by relay B Aplurality of taps are taken from various points of. the secondary winming of said transformer and respectively connected with a plurality ofsegments of the commutating device 1. Associated with the commutatingdevice is a rotating grounded arm 2 designed to support a brush 3, thesaid arm being rotated by means of a spring motor or other suitablesource of energy whereby the said brush may be brought in contact withthe successive segments of the commutating device. The electromotiveforce induced in the secondary winding of the transformer T sets up acurrent flow in the windings 1 1 of the transformer T which in turninduces an electromotive force into secondary windings 19 of the saidtransformer.

The mode of operation of this circuit is as follows: After a test hasbeen made upon the line L,, generally by means of a voltmeter, whichindicates that the trouble represented by the steady burning of the lamp20 is due to a receiver being off its hook, the operator will insert theplug P, into jack J, and operate the key K, to the left. This serves toconnectthe operators telephone set with the line L, and by listening andchallenging prior to the application of the howler potential, the saidoperator is thereby enabled to determine whether a party on this line isattempting to make a telephone call, or whether a receiver hasinadvertently been left off its book.

lVhen the operator inserted the plug P into jack J the lamp 5 would tendto light but due to the operation of relay H, as the result of theconnection of the tip and ring sides of the line at the contact 6 of thehook-switch of substation A, the lamp 5 is shunted through contact 8,and its lighting prevented. Another result of the operation of relay Ris the operation of relay R, which closes contact 9. Furthermore, whenkey K, was operated in the left hand direction to connect the operatorstelephone set with the line, contact 15 was closed thereby establishinga circuit from battery 13,, winding of relay R contact 15, conductor 17,and contact 9 to ground, which effected the operation of relay R By theclosing of the right hand contact of this relay, it is locked up over acircuit from the battery 13,, winding of relay R contact 18, contact 16,and contact 9 to ground.

After the operator has properly supervised the line, she will move thekey K, to its right hand position thereby closing contacts 10 and 13 ofthe said key and she will release the rotatable arm 2 so as to per mitits free movement. As the arm 2 of the commutating device 1 moves thebrush 3 in contact with segment 4;, a circuit will be established frombattery 13,, winding of relay R contact 10, left hand contact of relay Rand contact of segment 1- and brush 3 to ground, and relay R, will bethereby operated. By the closing of its left hand contact, the circuitincluding the generator G, and the primary winding of the transformer Twill be effectively closed. The operation of its right hand armaturewill close contact 11 and will open contact 16. By the closing ofcontact 11, relay R, will be locked up over a circuit from battery 13,,winding of relay R contact 10, contact 11, and contact 9 to ground. Bythe opening of contact 16 relay R will be released.

It should be clearly noted that by the operation and the locking ofrelay R current will flow through the primary winding of transformer T,which will induce a potential difference across the sectional secondarywinding of the said transformer. As the brush 3 is moved by the rotatingarm 2 into contact with segment 12, section a of the secondary windingof the transformer T will be connected in a circuit that e):- tends fromground through the rotating arm 2, brush 3 and segment 12 of thecommutating device, section a of the secondary winding, contact 13 andwindings 14 of the transformer T to ground. This flow of current throughthe winding 14 will set up an clectromotive force in the secondarywinding 19 of the said transformer which will be impressed upon line Land will produce a tone in the receiver at station A. As the armcontinues to rotate in the direction indicated by the'arrow the brush 3will be brought into contact with successive segments which results inconnecting into the circuit previously traced an increasing number ofsections of the secondary winding of the transformer thereby increasingby gradual steps the voltage impressed upon the windings 19 oftransformer T, ant likewise increasing the tone emitted by the receiver.The voltage reaches a maximum when all sect-ions ofthe secondary windinghave been connected into the said circuit, which occurs when the brushis in contact with the segment preceding segment 4. lVhen the brushmoves onto segment 4:, the voltage drops to zero and the cycle beginsagain.

I If during the period of application of the signaling current to theline, the subscriber at station A restores his receivr to its hook, thecontact 6 will be opened thereby releasing supcrvisory relay 3,. Contact8 will then be opened, thereby lighting lamp 5 and releasing relay R,which. opens its contact 9. Relay which, as previously pointed out, waslocked up over contact 9 will therefore be released, which opens theprimary circuit of transformer T and thereby effectively disconnects thesource of signaling potential from the line L Upon observing thelighting of the lamp 5, which indicates the restoration of the receiverto its hook, the operator will move the key K, to its left handpositionto connect her telephone set with the line to re-supervise thisconnection. If the supervision of the line indicates that the receiverat fault has been restored to its hook and that line conditions arenormal, the operator will withdraw the plug P, from the jack J andrelease the line for service.

If prior to the instant when the operator observedthelighting of thelamp 5 any party on the line L such as at stations A, or A, shouldattempt to use the line by removing his receiver from its hook, relays Rand R, will again be operated and contact 9'will be closed but thesource of signaling potential will not be reconnected thereby to theline. It will be remembered that relay R was originally operated by theclosing of the left hand contact of relay R and also by the movement ofbrush 3 into contact with segment 4. Since, relay R, has been'deenergize'd and can only be operated by the closing of contact 15 ofkey K,, it will be seen therefore that it is necessary for the operatorto reconnect her telephone set to the line L by operating key K, to theleft'before the signaling electromoti've force may again be applied tothe line. This means that proper supervision of the howler connection isensured and that unintentional, accidental application of the howlerelectromotive force to the line is entirely prevented.

From the foreging description it will be seen that my inventiondiscloses simple and effective means to prevent the application of asignaling current to a subscribers tele-,

phoneline upon which thereceiver has been allowed to remain off itshook, unless prior thereto; theoperator, whose duty is to apply the saidsignaling current, connects her telephone set with the said subscribersline, and thereby is placed in position to supervise the said line. Theinvention further more covers means for automatically dis continuing theapplication of the signaling potential to the line when the receiver atfault has been restored to its hook, and prevents a subsequentapplication of the signaling potential to the same line, upon theremoval of a receiver at any station connected with the said line,unless the operator supervises the line by again connect-ing hertelephone set thereto.

Although this invention has been shown embodied in a certain particularform, it is to be understood that it is not limited to this form but iscapable of embodiment in other and different forms Without de partingfrom the spirit of the appended claims.

What is claimed is:

1. In a signaling system, the combination with a subscribers telephoneline, of a source of signaling potential adapted to be switching meansprogressively varied in value, an operators telephone circuit andswitching means arranged to connect said source of signaling potentialwith the said telephone line when the said potential is at its minimumvalue and only after said telephone line has been supervised by theconnection of the said operators circuit therewith.

2. In a signaling system, the combination of a telephone line havingassociated there with a subscribers set, the receiver of which has beenremoved from its hook, and a howler signaling circuitadapted for.connection therewith comprising an operators telephone set, a source ofsignaling potential, the magnitude of which may be varied, and switchingmeans arranged to connect the said source to the said line when thepotential is a minimum value and only after the said operators set hasbeen connected to the said line.

3. In a signaling system, the combination of a telephone line havingassociated therewith a subscribers set, the receiver of which has beenremoved from its hook, and a howler signaling circuit adapted forconnection thereto comprising an operator's telephone set, a source ofsignaling potential and switching means arranged to successively connectto the telephone line the said operators set and the said source ofsignal ing potential, the said switching means be ing so arranged thatthe said source will be efiectively connected to the said line only whenthe potential is at its minimum, and only after said operators set hasbeen connected thereto.

a. In a signaling system, the combination of a telephone line havingassociated therewith a subscribers set, the receiver of which has beenremoved from its hook, and a howler signalingcircuit adapted forconnection thereto comprising an operators telephone set, a source ofsignaling potential, arranged to successively connect to the telephoneline the said operators set and the said source of signaling potential,the said switching means being so arranged that the said source will beeffectively connected to the said line only when the potential is at itsminimum and only after said operators set has been connected thereto,and means controlled by the restoration of the said receiver to its hookto effectively disconnect the said source of potential from the saidline.

5. In a signa ling system, the combination of a telephone line havingassociated therewith a subscribers set, the receiver of which has beenremoved from its hook, a source of varying potential adapted to causethe said receiver to produce a signaling tone, an operators telephonecircuit adapted to be connected with the said telephone line andswitching means arranged to connect the said operators circuit to thesaid line for supervisory purposes and to initiate the connection ot'the said source of potential to the said line and switching means tocomplete the connection of the said source after the said operatorscircuit has been disconnected from the said line.

6. In a signaling system, the combination 01": a telephone line havingconnected there with a plurality of sub-station sets, one of which is inoperated position, a circuit having a source of signaling potential andan operators telephone set connected therewith, means to connect thesaid circuit with the said line, switching means adapted to efi"ectively connect the said operators set with the said line and to initiatethe connection of the said source of signaling potential to the saidline and a second switching means arranged to disconnect the saidoperators set from the said line and to complete the effectiveconnection of the said source of potential to the said line.

7. In a signaling system, the combination of a telephone line havingconnected therewith a plurality of sub-station sets, one of which is inoperated position, a circuit. having a source of signaling potential andan operatmrs telephone set connected therewith, means to connect thesaid circuit with the said line, switching means adapted to efiectivelyconnect the said operators set with the said line and to initiate theconnection of the said source of signaling potential to the said line, asecond switching means arranged to disconnect the said operators setfrom the said line and to complete the efiective connection of the saidsource of potential to the said line and means adapted to effectivelydisconnect the said source of potential from the said line when theoperated sub-station set is restored to its nonoperated position and toprevent the reapplication of the said potential it any substation set issubsequently operated.

8. In a signaling system the combination of a subscribers telephone linecircuit the receiver of which is removed from its hook, a source ofvarying potential adapted for connection with said line circuit so as tocause said receiver to emit a signaling tone, an operators telephone setadapted also for connection with said line circuit, switching meansdesigned to connect the operators set with the line circuit anddisconnect it therefrom and also arranged to prevent the connection ofsaid source of potential to said line unless and until said operatorsset has been connected with said line and means controllable by theoperation of. said hook to disconnect said source from said line and torender impossible its reconnection until said operators set has againbeen connected with said line.

9. In a signaling system, the combination of a telephone linehavingconnected therewith a plurality of subscribers sets one of which has itsreceiver off its hook, a cord circuit having associated therewith asource of signaling potential an operators telephone set, and switchingmeans designed to ciiect the connection of said source with said linewhen the potential is at a minimum and after said operators set has beenconnect-ed in supervisory relation with said line, and means toeffectively disconnect said source from said line upon the restorationto its hook of the receiver of said one of said subscribers sets, and toprevent the reapplication of said potential to the line as the result ofthe subsequent removal of a receiver from its hook at any of saidstations.

In testimony whereof, I have signed my name to this specification this28th day of January, 1920.

ROGER G. RAMSDELL.

